Pressure-fluid-actuated mechanism



Patented Mar. 2, 1920.

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W. H. KELLER. PRESUHE FLUlD ACUATED MEGHANISM.'

APPLICATION FILED APR-2,1917- UNITED sTaTEs PATENT oEEIoE.

WILLIAM H. KELLER, 0F FOND DU LAC, WISCONSIN, ASSIGNOR T0 KELLER PNEUMATIC TOOL COMPANY, OF FOND DU LAC, WISCONSIN, A CORPORATION 0F MICHIGAN.

PRESSURE-FLUID-ACTUATED MECHANISM.

Specification ot Letters Patent.

Patented mm2, 1920.

matic or other pressure-fluid-actuated tools suchf as hammers, riveters, rock drills, tampers and the like. In such mechanisms there is a reciprocatory valve which controls the flow of pressure fluid `to and away from the cylinder or space in which the piston re: clprocates. In many fluid-actuated tools, the piston o r other reciprocatory member makes in the neighborhood of two thousand reciprocations per minute, and the effectiveness and. eiliciency of the tool depends almost entirely upon the regularity Vand positiveness of these reciprocations.

Fluid-actuated tools of the reciprocatorypiston type maybe divided into two' classes,

namely, those in which the piston travel extends to a point within the valve and those wherein the piston travel stops short of the valve. In the first mentionedclass of tools the proper operation of the valve has been interfered wlth through contact of the piston with the valve, and the valve has been' subject to breakage von account of being 4struck by the piston, particularly after the piston has become worn so as to have some side play in the piston chamber. In the ether class of tools, the piston has been liable to strike the box or casing inclosing the valve, the resulting jar producing jumping or flutterin of the valve and eventuallyI causing crysta breakage of the parts.

The 4object of my invention, generally stated, is to produce a pressure-fluid-actuated mechanism wherein maximum durability, eectiveness and strength are insured, and wherein the operation of the valve is rendered absolutely smooth and reliable and positively effective under varying degrees of motive fluid pressure.

This object has been attained by locating the valve Within a valve casing or box comprising a sleeve or tubular guide u on the periphery of which the valve is shda le and lization of the metal andv into which the piston travels in its reciprocations. Said sleeve or tubular guide thus keeps the valve and the piston out of contact with each other,-thereby obviating the breakage and the irregularities of valve action which are so objectionable in `tools of prior construction.

In the accompanying drawings, Figure 1 is a longitudinal central sectional View of a pneumatic tool embodying the Jfeatures of my invention, the piston and valve being shown in the position occupied when the piston is in its rearward position and `about to begin its forward stroke. Fig. 2 is a view similar to that of Fig. 1, but showing the piston and the valve in the positions occupied after the piston has completed its forward stroke and has started on yits return stroke.l Fig. 3 is a fragmental view of the valve mechanism, upon an enlarged scale.

The embodiment which has been selected to illustrate the invention comprises a cylinder or barrel l, a sleeve 2 projectin forwardly from and integral with the cy inder head or handle base 3, and a grasping handle 4. The cylinder 1 and the sleeve 2 may be connected in any suitable manner, as for example, by means `of the screw threads 5. The piston is indicated at 6. 7 is a working tool associated in any suitable manner with the forward end of the cylinder 1.

The inlet passage 8 for the motive fluid extends throughl the handle 4 and is controlled in any suitable manner, as, for example, by means of a throttle valve operated by a thumb lever 9.

While the valve casing may be of any suitable construction, it is herein shown as comprising a tubular body 10 and a cover or disk l1 arranged to fit against one end of the body l0. Integral with the cover ll is a sleeve 12 extending axially of the body 10. The bore of the sleeve l2 is alined with and of the same diameter as the bore of the cylinder l and virtually constitutes the rear portion of the cylinder or piston chamber.

The tubular body 'l0 and the sleeve l2 4are spaced apart so as to provide an annular chamber 13 to contain the valve lei. The latter is of annular or tubular construction and is adapted to slide in contact with the tubular body l0 and the sleeve 12, the tubulil@ liege lar body and the sleeve therefore constitutin guides for the valve.

he rear end of the cylinder 1 is placed in communication with the inlet passage 8 by means of ports15 in the cylinder head 3, said ports communicating with a suitable number of ducts 16 in thek tubular body 10 of the valve casing. The ducts 16` communicate with the rear end of the annular valve chamber 13 in which the valve 14 reciprocates. The'rear end of said chamber vcommunicates with the rear end of the cylinder by means of ports 17. In its reciprocation the valve 14 opens and closes communication between the ducts 16 and the ports 17.

Pressure' fluid is admitted to the forward end of the cylinder 1 'by means of passages 18 formed in the tubular body 10 of the valve casing, said passages communicating at one end with the ports 15. The opposite ends of the passages 18 are closed by the valve 14 when the lat-ter is in its forward position as shown in Fig. 1. The valve has in its periphery an annular groove 19, which, when the valve is in its rearward position, communicates with the passages 18 and with a suitable number of ports 20 in the body 10. The with passages 21 formed in the tubular body 10 and the cover 11. The passages 21 communicate with a suitable number of passages 225 extending to the forward endof the cylinder 1.

The motive fluid is exhausted from th space behind the piston through ports 23 formed in the sleeve 12. When the valve 14 is in its forward position as shownin Fig. 1, the exhaust ports 23 are covered by the valve, but whensaid valve is in its rearward position las illustrated in Fig. 2, the exhaust ports 23 register with an annular roove 24 formed in t-he inner periphery of tie valve The groove 24 communicates with a suitalble number of ports 25 in the valve. When the latter is in its rearward position, the ports 25 register with an annular groove 26 formed in the inner wall of the tubular body 10. The groove 26 communicates at all times through a suitable number of ports, 27 with an annular space 28 surrounding the valve casing. The annular space 28 communicates at all times with the atmosphere through the ports 29.

By reference to Fig. 1, it will be seen that when the valve 14 is in itsI forward po'- sition motive fluid is free to escape from the space in front of the. piston through the passages 21 and 22, the ports 20, the groove 19 in the valve 14, thegroove 26 in the tubular body 9, the ports 27, the annular space 28 and the ports 29.

The valve 14 is reciprocated by means of fluid pressure exerted upon its opposite ends. As will he evident from the draw ports 20 communicatel ings, the rear end of the valve 14 is exposed at all times to fluid pressure through the ducts 16.-4 yThe forward end of the valve is of larger area and is at times exposed to fluid pressure by means of a suitable number of passages 30 communicating at their forward ends with the cylinder 1 at .a point somewhat rearwardly of the position assumed by the iston at the end of its forward stroke. "llhe rear ends of the passages 30 communicate with passages 31 in the cover 11, the passages 31' communicating Vwith the forward end of the valve chamber 13 in which the valve 14 reciprocates.

32 is a passage communicating at its rear end with one of the ports 15 and at its forward end with the forward end of the Valve chamber 13. The passage 32 may be used to introduce a small amount offlive motive fluid from theport 15 to the valve chamber to assist in movin the valve if a quicker valve action is desired and the live motive fluid introduced into the Valve chamber through the passagesl 30 and 31 after the passages 30 are uncovered by the piston on its forward stroke is not considered suffcientI inV volume or pressure.

The operation of the mechanism is as follows When the parts are in the position shown in Fig. 1, the motive Huid flows from the supply duct 8 in the handle, thence through the ports 15 and the ducts into the valve chamber 13. The motive Huid then passes from the chamber 13 throng-h the ports 17 into the rear portion ofthe cylinder 1; andsassuming that the piston -6 is in the position shown in Fig. 1, the piston will be driven forwardly into contact with the shank of the working tool 7. While the' piston is traveling forward, the Huid in front of the piston flows through the passages 22, thence through the passa es 21, through the ports 20 into the annular groove 19| of the valve 14, thence in'to the groove 26 in the body 10 of the valve caslng, thence through the ports 27 and into the annular space 28 and thence through the ports 29 to the atmosphere.

It will be :noted that the ducts 16 of the valve casing are always open to live motive fluid pressure and that live motive fluid can always pass freely through said ducts to the rear end ofthe valve chamber 13. It will also be seen that vlive motive fluid pressure is always being exerted through the ducts 16 and valve chamber 13 upon the rear end of the valve 14. Hovever, when the piston 6 in its forward stroke has passed the forward end of the passages 30, live motive fluid is permitted to flow through said passages and the passages 31 into the forward end of the valve chamber 13 where said fluid exerts pressure on the forward end of the valve 14; and' as this end of the valve 16, and thence is larger than the rear end, the valve will move rearwardly against the pressure of the live. motive fluid which is being constantly exerted against the rear end of the valve. The valve has now moved from the position shown in Fig. l'to that illustrated in Fig. 2, thereby permitting live motive fluid to pass from the ports 15 through the passages 18 into the annular groove 19 in the valve, through the ports 20 and fthrough the passages 21 and 22 to the forward end of the cylinder, whereby the piston is caused to move from the position shown in Fig. 2 to the position shown in Fig. 1. xVVhile the piston is traveling rearwardly, the fluid at the rear of the piston is exhausted to the atmosphere through the ports 23, the groove 24, the ports 25, the groove 26, the ports 27, the annular space 28 and the ports 29. In moving from the position shown in Fig. 2 to that represented in Fig. l, the piston has uncovered the forward end of the passages 30, thereby permitting the motive fluid to escape from the valve chamber 13. through the passages 30 and 3-1`into the cylinder, thus relieving the pressure on the forward end of the valve 14; and the constant pressure of motive fluid on the rear end of the valve has caused the valve to move from the position shown in Fig. 2 to that illustrated in Fig. 1, thereby completing one cycle of operations.

It will be apparent that the valve-14 has a long bearing upon the tubular body 10 of the valve casing and the sleeve 12, and is thus effectively held against lateral or tilting movement, whereby efficiency and durability', with consequent economy in cost of maintenance, are obtained. Inasmuch as the sleeve 12 is interposed between the piston and the valve, it is impossible for the piston and the valve to come into contact with each other or for any jar or vibration to be transmitted to the valve, and hence the regularity and positiveness of the valve action cannot be' affected by the piston. The jumping or fluttering of the valve as well as the breakage which have heretofore been such objectionable features in {luid-actuated tools, are obviated.

Since the piston travels to a point within the valve casing, the cylinder 1 may be made shorter thanwould otherwise be possible,-a feature of particular importance when the tool is to be used in restricted spaces. It will be understood that if further shortening of the stroke were desirable, the piston could be provided with the usual annular peripheral groove to open the forward end of the passages 30.

The air trapped in the rear end of the piston chamber after the piston has closed the ports 17 eifectively cushions the return stroke of the piston.

While I have described the present emand that the valve mechanism'herein illustrated may be employed invarious types' of pressure-fluid-actuated apparatus.

I believe that I am the first to make a pneumatic or other fluid-actuated tool, the valve construction of which is such that the valve cannot possiblybe affected in any way whatever as regards the regularity and positiveness of the valve action.

I claim as my invention:A

1. A pressure-fluid-actuated mechanism having, in combination, a cylinder; a handle having a forwardly extended tubular portion of substantial len h, the forward end of which is secured ont e rear end of the cylinder and the rear. end of which has a closing wall so as--to form a housing rearwardly of the cylinder ;'-a piston in said cylinder; and valve mechanism in said housing for controlling the movements of the pisto'h, said mechanism comprising a tubular sleeve between the cylinder and said wall of the handle and alined with the cylinder, a cylindrical body surrounding said sleeve and- 4 spaced therefrom to form with the wall of the handle a valve chamber; and a valve member completely inclosed in said chamber and guided u on its opposite sides by saidv sleeve and bo y. I'

2. A pressure-fluid-actuated mechanism having, in combination, a cylinder; a handle having a forwardly extendedtubular portion of substantial length, the forward end of which is secured on therear end of the ,cylinder and the rear-end of which has a closing wall so as to.- form a housing rearwardly of the cylinder; a piston in said cylinder; and valve mechanism in said housing for controlling the movements of the piston,

said mechanism comprising a tubular sleeve between the cylinder and said wall of the handle and aline-d with the` cylinder, a cylindrical body surrounding said sleeve-and spaced therefrom to form-with the wall of the handle' a valve chamber, and a valve member completely inclosed in'said chamber cover for the rear end of the sleeve against which it abuts, said sleeve having a series of radial inlet yports in its rear end and said ioo sage and an inlet port leadin handle having a pressure' fluid supply pasforwardly from said passage; a tubular bo y surrounding said sleeve and spaced therefrom to form a valve chamber, said body having a duct in its rear end communicating with the port in the handle and 'opening into said valve chamber; and a tubular valve member completely inclosed within said chamber and guided on its opposite sides by said sleeve and body to control said radial ports in the sleeve.

4. A pressure-fluid-actuated mechanism having, in combination, a cylinder; a piston in said cylinder; and valve mechanism for controlling the movements of said piston comprising a' valve member and a valve casing at the rear end of -the cylinder wholly inclosing said valve member, means for constantly admitting pressure fluid to the rear end of said valve member, means for constantly admitting pressure fluid to the forward end of sald valve member, the last mentioned means being arran ed to admit a relatively restricted supply o pressure Huid only, and piston controlled means for admitting a furthersupply of pressure fluid to the forward end of said valve member.

In testimony whereof I have hereunto set -my hand.

WILLI-AM H. KELLER. 

